\documentclass{article}
\usepackage{amssymb,amsmath,amscd,concmath}
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\begin{document}
\begin{equation*} \textbf{x}_{k} = \textbf{F}_{k} \textbf{x}_{k-1} + \textbf{B}_{k}\textbf{u}_{k}  + \textbf{w}_{k} \end{equation*}
\end{document}
